The present invention relates to an indwelling needle assembly including an indwelling needle to be detained temporarily in a blood vessel for an infusion or the like. More specifically, the present invention relates to an indwelling needle assembly in which after an inner needle and an outer needle are pierced simultaneously in a tissue of a living body and the inner needle is removed from the outer needle while retaining the outer needle, the inner needle can be stored within a needle guard safely and easily.
An indwelling needle used for an infusion or the like generally has a double-needle structure comprising an outer needle and an inner needle inserted in a lumen of the outer needle, and when used, the assembly is pierced into a blood vessel with the inner needle. After the outer needle is inserted in the blood vessel to a prescribed position, the inner needle is removed from the lumen of the outer needle, and then an infusion line or the like is connected to a proximal end portion of the outer needle to allow an infusion, a liquid medicament or the like to flow into the blood vessel. Therefore, a soft resin product that has less possibility of damaging an inner wall of the blood vessel is used for the outer needle, and a metal product that can be easily pierced into the blood vessel is used for the inner needle.
After the outer needle is retained in a body of a patient, the removed inner needle is discarded. At this time, a member of a medical staff or a patient may be injured by inadvertently touching a sharp tip of the inner needle. Even when the tip of the needle is protected by a suitable means, an inner needle used for a patient suffering from a blood-borne disease such as acquired immune deficiency syndrome (AIDS) or hepatitis can be an infection vehicle that transmits these diseases not only through the tip but also through the needle itself.
Therefore, it is quite important to properly dispose of the inner needle that has been pierced into the patient. However, from a medical standpoint, treatment of the patient is given priority over the safety of the disposition of the inner needle in many cases.
In recent years, an indwelling needle assembly for discarding the used inner needle immediately and easily has been proposed (Japanese Patent Laid-Open No. 3-63066, Japanese Patent Laid-Open No. 6-78999, Japanese Patent Laid-Open No. 6-86821, Japanese Patent Laid-Open No. 11-57002).
Each of these indwelling needle assemblies comprises a tubular housing having an inner needle hub connected to the inner needle therein, and a needle guard slidably disposed between the housing and the inner needle hub and having a catheter connected to a distal end portion thereof, wherein after an outer needle of the indwelling needle assembly pierced into a patient is retained in the patient and the inner needle is removed, the inner needle is stored in the needle guard by sliding the needle guard toward the distal end of the housing. With these indwelling needle assemblies, when the inner needle is removed, the removed inner needle can easily be protected using one hand, and thus there is no risk of being injured by the tip of the inner needle or of being infected with disease by blood adhered to the inner needle.
However, since such an indwelling needle assembly is constructed to slide a needle guard that is longer than the inner needle toward the distal end of the housing by a length corresponding to the length of the inner needle, it is difficult for medical personnel who have small hands to slide the needle guard using one hand so as to completely protect the inner needle. In addition, in case of an emergent dialysis using a long indwelling needle to be retained in a femoral vein in an inguinal region, it is difficult even for medical personnel whose hands are not small to slide the needle guard using one hand to a position where the inner needle is completely protected.
On the other hand, in view of the problem described above, an indwelling needle assembly comprising a spring disposed between an inner needle hub and a proximal end portion of a needle guard has been developed (Japanese Patent Laid-Open No. 8-215315, Japanese Patent Laid-Open No. 9-103492). In the indwelling needle assembly, releasing a push-button locking mechanism allows the spring to urge the inner needle hub toward the proximal end of the needle guard.
However, in the indwelling needle assembly comprising such a push-button locking mechanism, it cannot be restored and thus the needle assembly may be put out of use in a case where a user releases the lock inadvertently by pushing the push-button.
In light of the circumstances described thus far, it is an object of the present invention to provide an indwelling needle assembly having such a structure that medical personnel can take the inner needle easily into the needle guard using one hand even when a long indwelling needle is used or even when it is used by a person who has small hands, and that cannot be put out of use by erroneous operation.
After an elaborate study to solve the problems described above, the present inventors found that the sliding distance of the needle guard required to store the inner needle can be reduced to about half that of the conventional indwelling needle assemblies by making the needle guard a double-tube structure including an inner tube and an outer tube, and providing a connector for connecting the inner tube and the inner needle hub in the needle guard via the proximal side of the outer tube, and thus the present invention is realized.
In other words, the present invention provides an indwelling needle assembly comprising an outer needle hub having an outer needle to be pierced into a tissue of a living body and retained therein fixed to the distal end portion of the hub, an inner needle hub having an inner needle being insertable into the lumen of the outer needle and having a sharp blade edge at the distal end fixed to the distal end portion of the hub, and a needle guard for accommodating the inner needle and the inner needle hub, characterized in that the needle guard has a double-tube structure including an inner tube and an outer tube, that the needle guard is provided with a connector for connecting the inner needle hub and the inner tube via the proximal side of the needle guard, in that the whole length of the needle guard can be extended by sliding the outer tube toward the proximal end of the inner tube, and in that as the whole length of the needle guard is extended, the inner needle hub is slid within the needle guard toward the proximal end of the needle guard by the connector.